Multi-page posts: A subdirectory for each post?

I am using WordPress as a CMS and would like to add a ‘Learn More’ page to each post that is created within a particular category. For example, when

http://www.mysite.com/cat/slug 

is created, I would also like for

http://www.mysite.com/cat/slug/learn-more 

to be created, too.

Ideally, this ‘learn more’ page would run on a template layout that I would create, and have it’s content populated by a custom field within the main post.

Is this at all possible? Is there a plugin available that will allow me to achieve this?

Thanks,
Ben